The absence of selenium – a little known trace element – in the body may help scientists understand the role of free radicals say an international team based at the University of Cambridge.

Selenium is vital to human health and is essential to cellular function in animals and humans: it is incorporated into proteins as the amino acid. A variation in the gene SECISBP2 prevents the production of most of the 25 known human selenoproteins say researchers who studied two individuals who had a rare genetic disorder that caused low levels of selenium in their body.

Their discovery may also shed light on the role of free radicals in the body. One of the features of selenium deficiency – as well as male infertility and muscle weakness – includes oversensitivity to ultraviolet light. When exposed to ultraviolet light the body produced free radicals, which are neutralised by antioxidants – the loss of a subset of selenoproteins that act as antioxidant enzymes mean individuals with a lack of selenium lack this defence.

This finding may point to new ways to treat selenium deficiency said lead researcher Professor Krishna Chatterjee:

“Trials of selenium supplementation in patients with selenoprotein deficiency have not been beneficial. However, we have shown that the patients have elevated levels of free radicals so treating them with antioxidants may prove to be more effective.”

He believes that study patients with selenoprotein deficiency may provide clues to the long- and short-term consequences of raised levels of free radicals.

“It has been suggested that excess free radicals can accelerate ageing or increase cancer risk,” he said, “We hope that studying these patients will helps us understand whether or not this is the case and how effective antioxidant therapies are at limiting free radical damage.”